Oh and by the way....
There is a grid no matter what you do. This "grid", is known as 3D Space
. You place the terrain and all units on the terrain at certain coordinates in 3D Space.
Say the terrain is at {0,0,0}(x,y,z).
An Advanced Lab could be at {-25, 3, 56}
This means it's -25 x, 3 units up or y, and 56 units z.
So in reality, we technically have a grid already in place... but I'm assuming you guys are talking about a more precise grid that would be easier to use ingame, based on 2D coordinate plane, because there isn't really a need for a 3D Coordinate Plane in this situation...